September 11, 2001 : Attack on America
Daily Environmental Monitoring Summary Wednesday; October 24, 2001

Daily Environmental Monitoring Summary

Wednesday, October 24, 2001

The U.S. Environmental Protection Agency (EPA) and other federal, state and local agencies have collected extensive environmental monitoring data from the World Trade Center site and nearby areas in Manhattan, Brooklyn and New Jersey. Since September 11, EPA has taken samples of the air, dust, water, river sediments and drinking water and analyzed them for the presence of pollutants that might pose a health risk to response workers at the World Trade Center site and the public. The samples are evaluated against a variety of benchmarks, standards and guidelines established to protect public health under various conditions. EPA is collecting data from 19 fixed air monitors in and around ground zero and is using portable sampling equipment to collect data from a range of locations.

Results as of 5:00 p.m. on 10/24

Air: Fixed Monitors in New York and New Jersey:

Asbestos - EPA analyzed 99 samples taken in and around ground zero from October 20 through October 22. All samples showed results less than 70 structures per millimeter squared, which is the Asbestos Hazard Emergency Response Act (AHERA) standard for allowing children to re-enter school buildings after asbestos removal activities. This brings the total number of air samples collected and analyzed for lower Manhattan to 1164, with 27 samples above the standard.

Four air samples taken in New Jersey on October 20 showed results less than the school re-entry standard. This brings the total number of samples collected and analyzed in New Jersey to 138, with zero above the standard.

Staten Island Landfill:

Air (Asbestos) - 57 samples were collected from October 19 to October 21: 55 of these samples showed results less than the AHERA standard. Two samples taken on October 20 exceeded the 70 structures per millimeter squared (70 S/mm2) AHERA standard. A sample taken at an indoor wash station showed a reading of 80 S/mm2; the other sample taken inside a supply tent showed a reading of 72 S/mm2.

Ambient Air Sampling:

VOCs - Sampling for volatile organic compounds (VOCs) was conducted on October 23 in the direct area of the debris pile at ground zero. Benzene exceeded the OSHA time-weighted average permissible level at two locations. EPA detected elevated readings of a compound, which has tentatively been identified as Freon-22 (chlorodiflouromethane). These air samples are collected down, within the debris pile using extended probes. EPA will do additional sampling and analysis to both confirm if the compound is Freon-22 and to determine the actual levels detected. EPA is working with the local agencies and health and safety officers working at ground zero to closely monitor this situation so that workers can take appropriate precautions.

PM 2.5 - Monitoring for fine particulate matter (particles less than 2.5 micrometers in diameter) was conducted on October 22 at Pace University, the Borough of Manhattan Community College, and the U.S. Coast Guard building located in Battery Park. All 24-hour average values were below the National Ambient Air Quality Standards (65 ug/m3) for all stations.

Particulate Monitoring - EPA used portable monitors to collect samples on October 23 in the following areas, which are also the locations of Fixed Air Monitors: L (north east side of Stuyvesant High), R (north west side of Stuyvesant High School), and N (South side of Pier 25). All readings were all below the OSHA time-weighted average permissible level for particulates.

Silicates - Ten samples collected on October 8 showed no detectable levels of silicates.

Dioxin - Ten samples were collected in the restricted work area near ground zero on October 8 and analyzed for dioxin. Four of the samples showed results above the level at which EPA would take some type of action to reduce people's exposure. This action level, however, is based on a 30-year exposure scenario. None of the ten samples were above the EPA's action level adjusted to a 1-year exposure duration. These levels do not pose a short-term health affect but should be monitored if they persist for a longer period of time.

Direct Air Readings - Using portable monitors, direct air readings were taken in and around ground zero on October 23. No significant readings, including those for carbon monoxide, were detected.


Dioxin - Two dust samples were collected on October 8 from rooftops in the vicinity of the former World Trade Center. Both samples were below the EPA residential cleanup goal of 1 part per billion.

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